Interposable mast

ABSTRACT

Boom-type lift vehicles, including such vehicles already existing, are convertible to boom-mast-type vehicles, by means of a mast having a simple connector system which enables it to replace removable forks leaving pivotal linkages at boom&#39;&#39; s-end undisturbed. The mast has nonpivoting attachment to a frame which remains pivotally mounted at boom&#39;&#39;s-end. The replaced forks can be used on the elevator carriage of the mast.

United States Patent Carriere 1 Mar. 7, 1972 [54] INTERPOSABLE MAST3,389,8l9 6/l968 Schumacher ..2l4/ 145 3,417,886 l2/l968 Stuart..2l4/l45 [721 invent Camm' 3,512,665 5/1970 Westendorf ..214/145 [73]Assignee: Pettibone Corporation, Chicago, Ill.

Primary Examiner-Robert G. Sheridan [22] Wed: 1969 AssistantExaminer-John Mannix [21] AppL 884,255Attorney-Darbo,RobertsontlzVandenburgh v [57] ABSTRACT [52] US. Cl..2l4/674, 214/1465, 214/620, I I

214/778 Boom-type l1ft vehlcles, lncludmg such vehicles already ens!- 51 1 1m. (:1. ..B65g 47/00 nvmible bmnmasmype hides, by means [58 Field61 Search ..214/672 673 674 620 145 mm having a simple wmcw' Systemwhich enables it 5 5 replace removable forks leaving pivotal linkages atboomsend undisturbed. The mast has nonpivoting attachment to a framewhich remains pivotally mounted at booms-end. The [56] References cuedreplaced forks can be used on the elevator carriage of the UNITED STATESPATENTS mast- 3,070,244 12/ l 962 Lull ..214/672 X 7 Claims, 4 DrawingF'lgllrts PATENTEDMAR H912 3,647, 099

Q 57 //v vs/vrom RUSSELL E CAR/WERE Affarney INTERPOSABLE MASTINTRODUCTION The invention of which this disclosure is offered forpublic dissemination, in the event patent protection is available,relates to forklift vehicles of the boom type, and more particularly toa simplified means for increasing the height of lift available in such avehicle by adding an elevating mast to it.

Forklift vehicles have commonly been of three types. In the mast type,the base portion of a telescopic mast is carried by the vehicle at afixed level, a telescoping portion elevates beyond the base portion, anda carriage on the telescoping portion moves from the bottom to the topof that portion during the elevating operation. In the boom type, theboom is pivoted at its rear end to the vehicle, or preferably toreaching link on the vehicle, and the fork device is power-pivoted tothe boom at its front end, this pivotal connection being used to keepthe forks horizontal during the pivotal lifting of the boom, andpreferably can also be used for dumping the forks. In the reachingversion of the boom type, an upstanding reaching link can bepower-pivoted to move the boom forwardly or rearwardly. The third classof forklift vehicles was a combination of the other two, a mast-on-boomtype. Here the mast is pivotally carried at the front end of the boomand the lifting by the mast action can be added to the lifting by theboom. The mast is power-pivoted so it can be kept vertical duringraising of the boom.

A great many forklift vehicles of the reaching boom type are already inservice. Occasionally the owner of one of these wants a higher lift thanis available from it. According to the present invention, it becomesquite easy for him to convert his boom device to a combined mast-on-boomdevice. The conversion and reconversion is so easy that if the ownerexpects to have a long period when he does not use the mast he maychoose to remove it, since the presenceof a .mast constitutes someobstruction to the great freedom of maneuvering which is one advantageof the simple boom type of machine.

Because of the greater freedom of movement of the simple boom type ofmachine, a purchaser purchasing a combined mast-on-boom type may preferto purchase it in the convertible form so that if he uses his machineunder circumstances such when, for long periods, he does not expect toneed the greater height provided by the mast he can convert to a simpleboom type machine with its more unimpeded maneuvering. Even though itmay be relatively rare that the upstanding mast at almost the very frontof the vehicle would strike anything, if it is present the operator mustbe constantly on his guard to be sure that he has adequate clearance.Hence the mast is decidedly objectionable, when it is not needed.

There may have been prior structures which, with changes could have beenconvertible. For example US. Pat. -No. 3,074,244 shows two forms which,perhaps only by hindsight, might have been made interchangeable. Suchconversion would have been both more complex and more expensive thanusing the present conversion. One total front end assembly would havebeen removed from the boomandanotherput in its place. According to thepresent invention, the fork-carrying frame of the boom device remains onthe boom. The forks alone are removed simply by pulling a shaft, themast is secured in its place almost as simply as the forks are removed,and the same forks are reattached to the elevating carriage of the mast.As compared to the boom type of machine, a minimum of accessoryequipmentis required, namely the bare mast without even its own forks.

DESIGNATION OF THE FIGURES FIG. I is an elevational view of a liftvehicle of the so-called reaching boom type.

FIG. 2 is an enlarged fragmentary elevational view of the boom-endportion of the vehicle illustrated in'FlG. 1 after it has been convertedin accordance with this invention to the boom-mast type.

DESCRIPTION OF PREFERRED EMBODIMENT Vehicle 10 illustrated in FIG. 1includes mobile chassis l2, boom means 14, and fork l6. Boom 14 issecured by pivoting means 18 to pivoting link 20 which, in turn, ispivotally secured to chassis 12. Hydraulic piston means 22, 24, 26 serveto operate the boom 14 and elements associated thereto.

Hydraulic piston means 22 powers the front-back reaching action of boom14. Hydraulic piston means24 powers the elevation of boom 14. Hydraulicleveler 26 secured pivotally at one end 28 to boom 14 is more or lesspermanently, and pivotally secured. by'pivot means 29 at end 30 to frame32. In theillustrated embodiment, boom 14 includes terminal portion 35which is fixed at an angle with respect to boom '14. The free end ofterminal portion 35 of boom 14 is also pivotally, more or lesspermanently secured to frame 32, by means of pivotal securing means 38.

A fork-frame '32 is dependably, pivotally attached at booms-end 35 andto the operating end 30 of hydraulic leveling unit 26. In theillustrated embodiment fork frame 32 is substantially rectangular,includes a pair of lateral sidewall members 40 and horizontally orientedstructural members 42 at the top and bottom thereof. In the side viewsonly the near elements are shown. It is to be understood, however, thatthe lift vehicle includes coacting piston means, especially reach means22 and lift means 24, identical to those illustrated in FIG. 1, on eachside of the vehicle, the corresponding members on each side beingoperable in unison, and boom parts more or less bridging across thevehicle to cooperate with both sets.

Spaced apart from side members 40 and closely adjacent thereto aresecondary vertical framing elements 44. Between members 40 and 44 thepivotal connections 29 and 38 are secured. These pivotal connections 29and 38, being more or less permanently secured, are preferably providedwith means for lubrication, e.g., grease fitting 46, and may have sealsto exclude water. and dust.

Forks 16 include horizontal load-engaging portion 48, vertical portion50. The upper extreme of verticalportion 50 is fashioned in the'generalshape of a loop52. Plate-element 54 is welded between thevertical elements 40, 44 immediately inwardly of elongated openings 55in members 40, 44. Thus, when fork 16 is secured to permanently attachedframe 32, pin 57 passing through openings 55, through-loop 52 in forkl6, and through second opening 55, -vertical member 50 of fork 1J6buttsagainstplate, 54 to limit downward pivot. How- 'ever, it isapparent that-mounting in accordance with the illustratedembodimentpermits .upwardpivoting of forks l6. The particular. mechanism by whichforks 16 ,aresecured to frame 32-may be conventional.

MAST ASSEMBLY According to this invention, .a :mast assembly 60, usuallytelescopic, can be used with .vehicles ofathe type described, in placeof their forks.

"In the illustrated embodiment, mast assembly 60 isof' the conventionaltelescoping type including a base portion-62 into which :upper,extendable frame 64 telescopes. Conventionally, upper frame 64 is movedin andout of base frame 62 by means of hydraulic :piston means '66.Hydraulic gpiston means 66 is powered by means ofhydraulic-fluidconveyed through'flexible conduit Ill-which isattachedpto hydraulicpiping 72 fixed toboom 14. Flexible conduit '70is-attachable to hydraulic piping'72-by'means of quick disconnectfittings 74, as-diagrammatically illustrated in -FIG. 3.-'Suchfittings-74 are commercially available and .provide'for almostinstantaneous disconnect of conduit 70 from piping 72 with automaticclosing of these elements when disconnected, and for automatic openingof the connection when terminal portions of lines 70, 72 are connectedthereby.

In the conventional telescoping mast construction, a vertically movablecarriage assembly 76, rides along the telescoping portion 64 of the maststructure. Carriage assembly 76 is moved, or perhaps more accurately,suspended" within telescoping structure 64 on chains 78, one end ofwhich is fixed to movable carriage assembly 76, the other end of whichis fixed to base portion 60. Chains 76 pass over conventional sprocketsmounted at upper end 80 of extendable telescoping frame member 64. Thus,as illustrated in FIG. 3, carriage 76, is positioned at the lower end 82of base portion 62 of mast 60 when telescoping section 64 is retractedto a position fully within base portion 62. However when telescopingportion 64 is extended out of base portion 62 due to the pushing actionof piston 66, one end of chain 78 remains fixed to base portion 62 and,because telescoping portion 64 and with it the sprockets referred toabove, are moved upwardly with respect to base portion 62, chain 78, inthe region secured to carriage 76, is likewise moved upwardly, but attwice the speed of portion 76 carrying with it carriage 76 so that it isalso moved upwardly with respect to telescoping frame 64. Thus carriage76 is in the position illustrated in FIG. 3, and in the positionillustrated by broken lines in FIG. 2 when the telescoping mast portion64 is in retracted condition, but is moved upwardly automatically to theupper portion 80 of telescoping portion 64 of mast 60, when thetelescoping portion is extended.

In accordance with this invention, pins 57 may be pulled, the forks 16removed, and the mast assembly 60, by its base portion 62 connected toframe 32 by reinserting pin 57. This pin now extends through mainsupport arms 84 which are welded to base portion 62 of mast 60. Openings86 in the extended portions 80 of arms 84 are sized to receive the pin57. Secondary attachment arms 90 are also carried by base portion 62.Connector arms 90 are secured to upper portion of frame 32 as by bolts92 through lugs 94 attached to horizontal member 42. Attaching theselugs preferably by welding is the only structural change which needs tobe made in existing machines. Thus, base portion 62 of mast, generally60, is secured nonpivotally through pin 57, and bolts 92, at two levelswidely spaced apart. Hence the function of bolt 92 and pin 57 insecuring mast 60, to boom 14, is purely that of fastening one element tothe other, with no rotating or pivoting function. Thus, while mast 62 isdisconnected from boom 14, it is not necessary to carefully protect theconnecting members from contamination by dirt, grit, etc., and it is notimperative that the connecting members be carefully cleaned andlubricated as it would be, were the connections made through pivotalmembers.

OPERATION An extremely large number of lift vehicles of the general typeillustrated in FIG. 1 are presently in successful operation. Simpleaddition to 32 of fastening means 94 at the top end thereof, as bywelding, and provision of hydraulic conduit means 72, 74, andconventional control elements (not shown because conventional) convertsvehicle to a condition in which these already available vehicles can bereadily, conveniently, safely, converted to the boom-mast type referredto above.

To make the changeover from the reaching boom, mast free conditionillustrated in FIG. 1' to the reaching boom-mast condition illustratedin FIG. 3, forks 16 are disengaged from frame 32 by withdrawal of pins57. Frame 32 and mast assembly 60 are brought together with openings 55adjacent openings 86. Pins 57 are reinserted through openings 55, 86 tosecure arm 86 to frame 32. Arms 90 are then secured to lugs 94 by meansof bolts 92, to complete the nonpivoting attachment of mast assembly 60to frame 32.

Forks 16 are then attached to carriage 76 by aligning loop 52 withopenings 96 and passing pins 97 through openings 96 and loop 52. Again,vertical portion 50 of forks l6 butt against a horizontal support member99 when attached as described above to carriage 76. Upper facing portion101 of carriage 76 serves to assist in the stabilization of the load,and to protect telescoping mast assembly 60, from the load.

Flexible hydraulic conduit 70 is then attached to hydraulic pipe 72 bymeans of quick disconnect element 74 and the entire unit is ready foroperation.

ACHIEVEMENT Thus, in accordance with this invention, widely availablevehicles of the type illustrated in FIG. I are readily convertible to agreater variety of uses, and, in the illustrated embodiment, areconvertible to a construction which permits substantial increase inheight-reach of the unit, e.g., for reaching to an upper level inconstruction work or for higher vertical stacking. Moreover, theconstant hazard occasioned by the presence of any mast, at the end of aboom, and the impediment of a mast to access to some places, can beavoided when the mast is not to be used by removing it. The versatilityof the convertible vehicle of this invention is substantially increasedover nonconvertible vehicles. Moreover, in accordance with thisinvention, none of the pivotal connections such as 29 and 38 need to bedisturbed. This is advantageous in several respects.

Iclaim:

1. In a lift vehicle, of the boom-mast type, having hydraulic pumpmeans, and having boom means having two ends thereof, one end of saidboom means being pivotally mounted to the vehicle, the other end beingelevatable and free, said vehicle having mast means secured to the freeend of the boom means, said vehicle having leveling means associatedwith the free end of the boom means and with the mast means, saidvehicle including carriage means elevatably secured on said mast means,and having load-engaging means releasably secured to said carriagemeans, the improvement comprising:

mounting frame means pivotally secured at the free end of the boom meansand operatively associated with the leveling means, the boom means andleveling means being permanently attached to said mounting frame means;

first receiving means on said mounting frame means for nonpivotally,releasably securing said mast means thereto;

said mounting frame means including means from maintaining respectiveelements of the boom means and of said leveling means in operatingspatial relationship with each other;

said mast means and said frame means being self supportable asstructurally integral units independently of each other;

drive means for moving said load-engaging means in a direction which isparallel with respect to said mast means, said drive means includingpower conduit means having a releasable connection therein near saidmounting frame means;

second receiving means on said mounting frame means for releasablysecuring said load-engaging means to said mounting frame means in theabsence of said mast means thereon.

2. In a lift vehicle, of the boom-mast type, having hydraulic pumpmeans, and having boom means with two ends thereof, one end of the boommeans being pivotally mounted to said vehicle, the other end beingelevatable and free, mast means secured to the free end of the boommeans, said vehicle having leveling means at the free end of the boommeans, said leveling means being operatively associated with said mastmeans, carriage means elevatably secured on said mast means,loadengaging means releasably secured to said carriage means, the mastmeans including a base portion and an extendable telescoping portionthereof, said carriage means being secured to said extendable portionthereof, said vehicle including hydraulically powered and controlledmeans for cooperatively extending the telescoping portion of the mastwith respect to the base portion of the mast and simultaneouslyelevating said carriage means with respect to said telescoping portionof the mast, the improvement comprising:

mounting frame means pivotally secured at the free end of the boom meansand operatively associated with said leveling means, said boom means andleveling means being permanently attached to said mounting frame means;

first receiving means on said mounting frame means for nonpivotally,releasably securing said mast means thereto;

said mounting frame means including means for maintaining respectiveelements of said boom means and said leveling means in operating spatialrelationship with each other; said mast means and said frame means beingself supportable as a structurally integral unit independently of eachother;

said hydraulically controlled drive means including hydraulic conduitmeans having a releasable connection therein near said mounting framemeans;

second receiving means on said mounting frame means for releasablysecuring said load-engaging means to said frame in the absence of saidmast means thereon.

3. In a lift vehicle, of the boom-mast type, having boom means with asecured end and a free end, the secured end being pivotally mounted tothe vehicle, the free end being elevatable, said vehicle including meansfor elevating the boom means, and including mast means secured to thefree end of the boom means, carriage means elevatably secured on saidmast means, load-engaging means secured to said carriage means, poweredmeans for manually controlled operation of said carriage means, theimprovement comprising:

mounting frame means pivotally secured at the free end of the boom meansand operatively associated with said leveling means, said mounting framemeans being sub stantially rectangular and having an upper and lowerhorizontal portion thereof;

first and second releasable attaching means for nonpivotally securingsaid mast means to said mounting frame means, the first attaching meansbeing positioned adjacent the lower portion of said frame and includingmeans for receiving a connecting portion of said mast means, andalternatively for receiving a connecting portion of said load-engagingmeans in the absence of said mast means thereon, said secondmast-engaging means being secured adjacent the upper horizontal portionof the frame, said drive means including power conduit means having areleasable connection therein near said mounting frame means.

4. In a lift vehicle of the boom-mast type, having boom means with asecured end and a free end, the secured end being pivotally mounted tothe vehicle, the free end being elevatable, said vehicle including meansfor elevating the boom means, and including mast means secured to thefree end of the boom means, said vehicle including leveling meansassociated with said free end of said boom means and with said mastmeans, carriage means elevatably secured on said mast means,load-engaging means secured to said carriage means, drive means formoving said carriage means with respect to said mast means, theimprovement comprising:

mounting frame means pivotally secured at the free end of the boommeans, and operatively associated with said leveling means, saidmounting frame being substantially rectangular and having an upper andlower horizontal portion thereof;

first and second releasable attaching means for nonpivotally securingsaid mast means to said frame means, the first attaching meanscomprising a nonrotatable arm secured to a lowermost portion of saidmast means, mating means for. securing said arm to detent meanspositioned adjacent the lowermost portion of said mounting frame means,said second mast-engaging means comprising nonrotatable arm meanssecured to said mast means at a point spaced far apart from said firstmast-engaging means and comprising detent means fixed to the upperportion of said mounting frame means for mating with said second armmeans, said load-engaging means comprising forks releasably secured tosaid carriage means, said forks having means for engaging said firstdetent means;

drive means for moving said load-engaging means with respect to saidmast means, said drive means including power conduit means having areleasable connection therein near said mounting frame means.

5. A self supportable mast for use in conjunction with a convertiblelift vehicle of the boom type, said vehicle having a hydraulic pump,said vehicle having a receiving frame pivotally secured to the operatingend of a boom on said-vehicle, .said receiving frame releasably carryingload-engaging means secured thereon by releasable securing means on saidframe, said mast including:

telescoping vertical members;

carriage means movably secured to the telescoping members;

load-engaging means carried by said carriage means;

hydraulic power means for operating said telescoping members and saidcarriage means;

hydraulic connection means in said power means for operativelyconnecting elements on the mast to said pump on said vehicle, and fordisconnecting said elements from said pump;

first attachment means for engaging said securing means for nonpivotallysecuring said mast to said receiving frame; and,

second attachment means for attaching the load-engaging means to thecarriage, the second attachment means being substantially identical tosaid securing means.

6. A material handling vehicle including a chassis and a boom pivoted atits rear portion to the chassis, a frame pivoted to the front end ofthe. boom, means for changing the angularity of the frame as to the boomas the boom swings up and down, 'forks or other load-engaging meanscarried by the frame and secured to it by a removable pin;

and a mast for attachment to the frame when the load-engaging means'havebeen removed, the mast having support and securing formations on itsrear side for engagement by said pin upon restoring the pin, and havingon its forward side an elevating carriage movable along the mast andprovided with formations for receiving said forks and securing them withanother pin;

said mast having hydraulic piston means for the raising of the carriage,and said vehicle and boom having a pump and conduit means extendingapproximately to the frame and'provided with quick disconnect means forconnection with the piston means.

7.For cooperation with a material handling vehicle of the boom typehaving a framepivotedwith'he boom and provided with means for changingthe angle of the frame with respect to the' boom as the boom swings upand down and having hydraulic pressure means including quick disconnectmeans in the vicinity of the frame, the frame having a removable pin forsecuring forks or the like thereto:

a mast having on its rear side formations adapted to receive the pinuponbeing restored after removal of the load-engaging means, having pistonmeans adapted to be connected to said quick disconnect means, having acarriage adapted to beraised and'lowered along the mast by the pistonmeans, and said carriage having a removable pin and formations forreceiving the load-engaging means removed from the frame; said formationand pin of the carriage being matingly similar to the formation at therear of the mast whereby the mast and the load-engaging means which fitits carriage will be interchangeable on the frame.

1. In a lift vehicle, of the boom-mast type, having hydraulic pumpmeans, and having boom means having two ends thereof, one end of saidboom means being pivotally mounted to the vehicle, the other end beingelevatable and free, said vehicle having mast means secured to the freeend of the boom means, said vehicle having leveling means associatedwith the free end of the boom means and with the mast means, saidvehicle including carriage means elevatably secured on said mast means,and having loadengaging means releasably secured to said carriage means,the improvement comprising: mounting frame means pivotally secured atthe free end of the boom means and operatively associated with theleveling means, the boom means and leveling means being permanentlyattached to said mounting frame means; first receiving means on saidmounting frame means for nonpivotally, releasably securing said mastmeans thereto; said mounting frame means including means frommaintaining respective elements of the boom means and of said levelingmeans in operating spatial relationship with each other; said mast meansand said frame means being self supportable as structurally integralunits independently of each other; drive means for moving saidload-engaging means in a direction which is parallel with respect tosaid mast means, said drive means including power conduit means having areleasable connection therein near said mounting frame means; secondreceiving means on said mounting frame means for releasably securingsaid load-engaging means to said mounting frame means in the absence oFsaid mast means thereon.
 2. In a lift vehicle, of the boom-mast type,having hydraulic pump means, and having boom means with two endsthereof, one end of the boom means being pivotally mounted to saidvehicle, the other end being elevatable and free, mast means secured tothe free end of the boom means, said vehicle having leveling means atthe free end of the boom means, said leveling means being operativelyassociated with said mast means, carriage means elevatably secured onsaid mast means, load-engaging means releasably secured to said carriagemeans, the mast means including a base portion and an extendabletelescoping portion thereof, said carriage means being secured to saidextendable portion thereof, said vehicle including hydraulically poweredand controlled means for cooperatively extending the telescoping portionof the mast with respect to the base portion of the mast andsimultaneously elevating said carriage means with respect to saidtelescoping portion of the mast, the improvement comprising: mountingframe means pivotally secured at the free end of the boom means andoperatively associated with said leveling means, said boom means andleveling means being permanently attached to said mounting frame means;first receiving means on said mounting frame means for nonpivotally,releasably securing said mast means thereto; said mounting frame meansincluding means for maintaining respective elements of said boom meansand said leveling means in operating spatial relationship with eachother; said mast means and said frame means being self supportable as astructurally integral unit independently of each other; saidhydraulically controlled drive means including hydraulic conduit meanshaving a releasable connection therein near said mounting frame means;second receiving means on said mounting frame means for releasablysecuring said load-engaging means to said frame in the absence of saidmast means thereon.
 3. In a lift vehicle, of the boom-mast type, havingboom means with a secured end and a free end, the secured end beingpivotally mounted to the vehicle, the free end being elevatable, saidvehicle including means for elevating the boom means, and including mastmeans secured to the free end of the boom means, carriage meanselevatably secured on said mast means, load-engaging means secured tosaid carriage means, powered means for manually controlled operation ofsaid carriage means, the improvement comprising: mounting frame meanspivotally secured at the free end of the boom means and operativelyassociated with said leveling means, said mounting frame means beingsubstantially rectangular and having an upper and lower horizontalportion thereof; first and second releasable attaching means fornonpivotally securing said mast means to said mounting frame means, thefirst attaching means being positioned adjacent the lower portion ofsaid frame and including means for receiving a connecting portion ofsaid mast means, and alternatively for receiving a connecting portion ofsaid load-engaging means in the absence of said mast means thereon, saidsecond mast-engaging means being secured adjacent the upper horizontalportion of the frame, said drive means including power conduit meanshaving a releasable connection therein near said mounting frame means.4. In a lift vehicle of the boom-mast type, having boom means with asecured end and a free end, the secured end being pivotally mounted tothe vehicle, the free end being elevatable, said vehicle including meansfor elevating the boom means, and including mast means secured to thefree end of the boom means, said vehicle including leveling meansassociated with said free end of said boom means and with said mastmeans, carriage means elevatably secured on said mast means,load-engaging means secured to said carriage means, drive means formoving said carriage means with respect to said mast means, theimprovement comprising: mounting frame means pivotaLly secured at thefree end of the boom means, and operatively associated with saidleveling means, said mounting frame being substantially rectangular andhaving an upper and lower horizontal portion thereof; first and secondreleasable attaching means for nonpivotally securing said mast means tosaid frame means, the first attaching means comprising a nonrotatablearm secured to a lowermost portion of said mast means, mating means forsecuring said arm to detent means positioned adjacent the lowermostportion of said mounting frame means, said second mast-engaging meanscomprising nonrotatable arm means secured to said mast means at a pointspaced far apart from said first mast-engaging means and comprisingdetent means fixed to the upper portion of said mounting frame means formating with said second arm means, said load-engaging means comprisingforks releasably secured to said carriage means, said forks having meansfor engaging said first detent means; drive means for moving saidload-engaging means with respect to said mast means, said drive meansincluding power conduit means having a releasable connection thereinnear said mounting frame means.
 5. A self supportable mast for use inconjunction with a convertible lift vehicle of the boom type, saidvehicle having a hydraulic pump, said vehicle having a receiving framepivotally secured to the operating end of a boom on said vehicle, saidreceiving frame releasably carrying load-engaging means secured thereonby releasable securing means on said frame, said mast including:telescoping vertical members; carriage means movably secured to thetelescoping members; load-engaging means carried by said carriage means;hydraulic power means for operating said telescoping members and saidcarriage means; hydraulic connection means in said power means foroperatively connecting elements on the mast to said pump on saidvehicle, and for disconnecting said elements from said pump; firstattachment means for engaging said securing means for nonpivotallysecuring said mast to said receiving frame; and, second attachment meansfor attaching the load-engaging means to the carriage, the secondattachment means being substantially identical to said securing means.6. A material handling vehicle including a chassis and a boom pivoted atits rear portion to the chassis, a frame pivoted to the front end of theboom, means for changing the angularity of the frame as to the boom asthe boom swings up and down, forks or other load-engaging means carriedby the frame and secured to it by a removable pin; and a mast forattachment to the frame when the load-engaging means have been removed,the mast having support and securing formations on its rear side forengagement by said pin upon restoring the pin, and having on its forwardside an elevating carriage movable along the mast and provided withformations for receiving said forks and securing them with another pin;said mast having hydraulic piston means for the raising of the carriage,and said vehicle and boom having a pump and conduit means extendingapproximately to the frame and provided with quick disconnect means forconnection with the piston means.
 7. For cooperation with a materialhandling vehicle of the boom type having a frame pivoted with he boomand provided with means for changing the angle of the frame with respectto the boom as the boom swings up and down and having hydraulic pressuremeans including quick disconnect means in the vicinity of the frame, theframe having a removable pin for securing forks or the like thereto: amast having on its rear side formations adapted to receive the pin uponbeing restored after removal of the load-engaging means, having pistonmeans adapted to be connected to said quick disconnect means, having acarriage adapted to be raised and lowered along the mast by the pistonmeans, and said carriage having a removable pin and formations forreceiving the load-engaging means removeD from the frame; said formationand pin of the carriage being matingly similar to the formation at therear of the mast whereby the mast and the load-engaging means which fitits carriage will be interchangeable on the frame.